<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        *{
            margin: 0px;
            padding: 0px;
            border: 0px;
        }
        body{
            margin: 0px;
        }
    </style>
</head>
<body>
<div>
<div style="height: 100px;width: 100%;background-color: #2B2F3E;color: white">
    <h3>这里是底部</h3>
</div>
</div>
</body>
</html>